Equivalent Section Research Articles

Experimental study on bending properties of bamboo-wood composite beams with different tectonic patterns

This study investigated the mechanical properties of bamboo-wood composite beams by conducting four-point bending static load tests on eight laminated beams. It was shown that a new bamboo-wood composite material was obtained by laminating denser laminated bamboo to the surface of timber panels employing hot pressing. Failure of the beams was mainly due to interlaminar shear damage and brittle fracture at the bottom. The test results showed that the polyurethane and epoxy binders ensured good interlaminar bonding properties. In the same adhesive specimen, the increase in the number of bamboo panels increased the ultimate load-carrying capacity of the bamboo-wood composite beams. The predicted load capacity using the equivalent section calculation method agreed well with the experimental results and was effective for assessing the mechanical properties of bamboo-wood composite laminated beams.

Experimental study on tensile mechanism of UHPC grouted sleeve splice

The grouted sleeve splice is a competitive splice in the prefabricated structure that plays a key role in ensuring the stability of the whole structure. Despite the large amounts of experiments performed, its force mechanism has rarely been explored. In this study, a novel method was developed to calculate the constitutive model of grouted sleeve splice, and a comprehensive understanding of the force mechanism was analyzed. Tensile tests of 24 specimens were conducted to explore the mechanical properties of the grouted sleeve splice. The results showed that the anchorage length of rebar with ultra-high-performance grout material can be shorter than that recommended in design standards. The anchorage length and eccentricity of rebars have a significant impact on the mechanical performance of the grouted sleeve splice, which deserves special attention in the structure design and construction. The non-anchorage section of the grouted sleeve splice offers little contribution to the bearing capacity. Based on the concept of equivalent section elastic moduli, a theoretical calculation method was established to reveal the stress–strain relationship of the grouted sleeve splice. The errors between the theoretical model and test results vary from 0.20% to 18.90%. This study provides new perspectives for theoretical research on the mechanism of grouted sleeve splice.

Elastic Lateral‐Torsional Buckling of Girders with Corrugated Web: Equivalent Section Properties Approach

AbstractOne of the benefits of using corrugated web girders is the increase of lateral‐torsional buckling resistance. Different approaches have been presented to obtain the value of the critical moment as a function of the cross‐section geometry. Previous research works consider that the increase in buckling resistance must be accredited to a higher warping constant. The paper presents a systematic finite element numerical analysis of girders with different corrugated web shapes. Bending with respect to the weak axis shows that corrugated web implies higher moment of inertia. Torsion analysis results clearly demonstrate that the increase of torsion resistance is mainly due to higher torsional constant. The paper compares the elastic critical moment values obtained by using finite element elastic buckling analysis with the values provided by theoretical expressions introducing equivalent section properties. Results show that the equivalent section properties approach provides values very close to those obtained using finite elements. Finally, the paper presents closed form expressions to directly compute approximate equivalent section properties of any girder with corrugated web, which compare very satisfactory with those values obtained with finite element buckling analysis.

Future-Proof Doctrine or Relic of an Equitable Past? Unconscionable Conduct in the Fair Trading Amendment Act 2021

The Fair Trading Amendment Act 2021 introduced a New Zealand prohibition on "unconscionable conduct" in trade. Previously, the law on unconscionable conduct was found in the equitable doctrine of unconscionable bargain. This article describes how New Zealand law has moved away from equitable unconscionability with this new prohibition. This article critically analyses some of the legal, social and economic justifications for introducing the prohibition, finding that some of the Ministry of Business, Innovation and Employment's justifications are not persuasive. The s 7 prohibition is based strongly on an equivalent section in the Australian Competition and Consumer Act 2010 (Cth). It is argued that long-standing doctrinal issues with Australia's prohibition provided a strong basis for New Zealand to pursue a different standard. Finally, this article explores the "unfair commercial practices" doctrines in the United States and European Union through the lens of anti-consumer practices in digital marketplaces. The conclusion is that the unfair commercial practices doctrine captures a wider range of anti-consumer conduct than does unconscionable conduct.

Desain Overlay Perkerasan Lentur Pada Jalan Joyoboyo Timur Kediri Dengan Metode Analisa Komponen

Road pavement damage is an important thing to pay attention to. Improper planning, increasing traffic volume loads to lack of care and maintenance are factors that cause road damage. Road damage has an impact on the safety of road users. On the Joyoboyo East Kediri road, there are several roads that suffered significant damage. This study aims to design the repair of damage to the East Kediri Joyoboyo road. Repairs are carried out by adding a layer of pavement to the potholes. The component analysis method is used to determine the required pavement thickness. With the component analysis method, the design equivalent cross section will be calculated based on traffic data, as well as soil bearing capacity, regional factors and surface index. So that the pavement thickness index is obtained to determine the required pavement thickness. The result of this research is that the cross equivalent is 116.730, the regional factor value is 0.5 and the Surface Finish Index is 1.5. From the results of these calculations, Nomogram 5 was used and the Pavement Thickness Index value was 5.2. So that the required overlay thickness is 5 cm. These results can be used as a reference in repairing pavement damage on the Joyoboyo Timur Kediri road, so that it can support the safety of road users and facilitate transportation.

The Conjugate Beam Effective Thickness Method

The structural performance of laminated glass is strongly dependent on the shear coupling offered by the interlayer between the bounding layered and monolithic limits of the glass plies. The most common simplified design approach consists of defining the effective thickness, i.e., the thickness of a monolithic section with equivalent flexural section properties. The Enhanced Effective Thickness (EET) method has been verified to estimate deflection in laminated glass for a range of load and boundary conditions for two-, three-, and multi-ply beams; however, for some static schemes, the EET method is less accurate for predicting stress. The recently proposed Conjugate Beam Effective Thickness (CBET) method, initially developed for cantilevered laminated glass balustrade applications, accounts for the relative displacement of glass plies across the interlayer for a range of loads and statically determinate boundary conditions. In this paper, the CBET method is extended to the evaluation of two-ply simply supported beams under concentrated, uniformly, and tapered distributed out-of-plane loads. Predicted deflection- and stress-effective thickness obtained from effective thickness methods is compared with finite element model results in illustrative examples, demonstrating improved accuracy. Closed-form formulas are summarized in tables to facilitate the practical application of the CBET method in the design practice.

Novel perturbation solutions for deep-buried non-circular tunnels under biaxial in situ stress field based on Mohr-Coulomb criterion

Based on Mohr-Coulomb criterion, the generalized perturbation solutions for elastic-brittle-plastic rock surrounding deep-buried non-circular tunnels are presented in this study. The asymptotic expansions and a novel equivalent elliptical method adaptable for arbitrary shaped tunnel are provided for the perturbation analysis. Concerning the plastic analysis, the recurrence formulas and a simplified semi-analytical approach are developed for solving arbitrary-order approximations of stress functions conveniently. Subsequently, a novel undetermined coefficient method incorporating the stress continuity on elastoplastic interface is presented for determining the plastic radius and stress functions in elastic zone. On the basis of the preceding solutions, the extended solutions with equivalent elliptical method are developed for further expanding the applicable range of solutions. Besides, the perturbation analysis based on generalized Hoek-Brown criterion can be implemented in terms of the equivalent angles of friction and cohesive strengths. The whole computing process is provided in flow chart for the convenience of programming. The reliability of the solutions has been verified by comparing with the calculating results of numerical simulation. Significant improvements can be noticed for the predicted plastic radius compared with the results by the existing equivalent circular method. From a theoretical point of view, the developed perturbation solutions with equivalent section method complete the framework of the elastoplastic analysis for non-circular tunnels. From the perspective of practicality, the proposed solutions can provide preliminary insight for the rapid stability evaluation, plastic radius prediction, and tunnel outline design in practical engineering.

Research on Torsional Characteristic and Stiffness Reinforcement of Main Girder of Half-Through Truss Bridge

The stronger stability of a half-through truss bridge can improve the bridge performance for resisting extreme loads, such as earthquakes and shock. To improve the bridge stability, it is necessary to improve the torsional stiffness of the half-through truss bridge. To study the torsional characteristics of the main girder of the half-through truss bridge, the half-through truss is equivalent to an open slot thin-walled member, and the calculation formula of the free torsional moment of inertia of the main girder is deduced. Because the main truss can resist warping deformation through bending, it has a great contribution to the torsional stiffness. Based on the vertical bending action of the main truss, the calculation formula of the correction of the torsional moment of inertia of the main girder is deduced. Taking a half-through truss pedestrian bridge as an example, the torsional moment of inertia of the bridge under different width-span ratios is calculated by theoretical and finite element analysis. The results show that when calculating the torsional moment of inertia of the main girder of the half-through truss bridge, the free torsional moment of inertia calculated by the equivalent open slot section is very different from the actual torsional stiffness, and the bending correction value must be considered. The theoretical solution after taking into account the corrected value is well-fitted with the finite element results. The theoretical formula can be used to explain the torsional mechanism of this kind of bridge. According to the mechanism research, the method of installing X-shaped longitudinal supports between the upper transverse girders to improve the torsional stiffness is finally formulated. Installing the X-shaped longitudinal supports not only can keep the size of the half-through truss bridge unchanged but can also have a considerable enhancement effect, which will significantly improve the torsional stiffness and stability of existing bridges.

Grinding performance and theoretical analysis for a high volume fraction SiCp/Al composite

SiCp/Al composite is widely used in space shuttle slides, automotive and machine tools. In this paper, ground surfaces of SiCp/Al composite, obtained with different grinding process parameters, are characterized in terms of friction and wear performances under dry and lubricated conditions. The wear mechanism of SiCp/Al composite is firstly found the combination of cohesive and abrasive wear, then a method to calculate the wear volume of SiCp/Al composite is proposed, and a comprehensive wear evaluation system of SiCp/Al composite is established, in which the three indicators of friction coefficient, wear depth, and equivalent wear section area are adopted to evaluate usability performance. The prediction models of the wear indicators were established and the errors between the experimental and predicted results are within 7%. Finally, the NSGA-II multi-objective algorithm is used to optimize surface performance of the SiCp/Al composite, and the optimized grinding process parameters are obtained as the wheel speed of 33 m/s, the table speed of 0.4 m/min and the grinding depth of 9 μm.

Design of Ridge Waveguide Radial Combiners

This article presents a comprehensive treatment to the subject of designing ridge waveguide radial combiners. A theoretical framework for the design process is first presented paving the way to a straightforward design procedure for radial combiners with both moderate and very wide bandwidths (BWs) realized in ridge waveguides. Two types of ridge waveguide radial combiners are presented, one with linearly tapered ridged sections and the other with staircase-like ridged sections. The methodology to design the radial combiner is presented. It starts with designing the individual ridge waveguide input ports, and then designing an equivalent transformer section that provides matching between the individual ridge waveguide ports and a common coaxial line output port. Design considerations for the different cross sections make it possible to achieve the required impedance levels for good matching across wide BWs. Three complete design examples are presented. Two proof-of-concept prototypes were designed, simulated, fabricated, and tested demonstrating excellent measured results without any tuning.

Analysis of the structural behavior of flat and circular self-supporting roof using finite elements

The development and innovation of Science, specifically in the branch of construction in Civil engineering, has led the implementation of new alternatives in analysis, design and construction of industrial buildings. For this reason, in this research it was proposed to carry out a study of structural behavior of two types of self-supporting roofs: flat and circular, which were analyzed using computational tools for simulation through finite elements, in which initially the structure made up of columns, beams and steel sheets was completely modeled with an equivalent cross section, which made up the self-supporting roofs; then only the steel sheets with real cross section were discretized, and it was noted that in the extremes were the greatest stresses generated by the application of horizontal and vertical loads; and the maximum displacement of the circular roof was 14.32 % of the flat one.

Solid Bitumen Occurrences in the Pyrenean Basin (Southern France): A Case Study across the Pliensbachian–Toarcian Boundary

The study across the Pliensbachian–Toarcian boundary sedimentary record in the Bizanet section of the Pyrenean Basin (southern France) revealed the presence of solid bitumen. This secondary organic matter was characterized using petrographic (transmitted and reflected white lights, incident blue light, and scanning electron microscopy) and geochemical (total organic carbon, total sulfur, and insoluble residue) techniques. The spore coloration index (SCI) was also determined. With the characterization of the optical properties and reflectance of the solid bitumen, it was possible to distinguish four different families (A–D) that display a wide range of reflectance values, from 0.21% to 2.64% BRr, i.e., from glance pitch to meso-impsonite. SCI values were higher than 9–9.5 (%Req > 1.50%). The comparison between the equivalent vitrinite reflectance values of the solid bitumen and SCI showed that this index and the solid bitumen D values are concordant, indicating that solid bitumen D can be considered an indigenous bitumen. The other three families of solid bitumen (A–C) are considered as having migrated. The laterally equivalent Pont de Suert section (South Pyrenean Zone) displays no trace of solid bitumen which points to the important role of the morphotectonic context of the Bizanet section in the migration of these hydrocarbons, namely, the presence of a major thrust fault in the eastern Corbières close to the section’s location.

Construction of Uniaxial Interaction Diagram for Slender Reinforced Concrete Column Based on Nonlinear Finite Element Analysis

Slender reinforced concrete column may fail in material failure or instability failure. Instability failure is a common problem which cannot be analyzed with first-order analysis. So, second-order analysis is required to analyze instability failure of slender RC column. The main objective of this study was to construct uniaxial interaction diagram for slender reinforced concrete column based on nonlinear finite element analysis (FEA) software. The key parameters which were studied in this study were eccentricity, slenderness ratio, steel ratio, and shape of the column. Concrete damage plasticity (CDP) was utilized in modeling the concrete. Material nonlinearity, geometric nonlinearity, effect of cracking, and tension stiffening effect were included in the modeling. The results reveal that, as slenderness ratio increases, the balanced moment also increases, but the corresponding axial load was decreased. However, increasing the amount of steel reinforcement to the column increases the stability of the column and reduces the effect of slenderness ratio. Also, the capacity of square slender RC column is larger than rectangular slender RC column with equivalent cross section. However, the result is close to each other as slenderness ratio increased. Finally, validation was conducted by taking a benchmark experiment, and it shows that FEA result agrees with the experimental by 85.581%.

Flexural performance of lightweight aggregate concrete columns

This study examined the effect of the concrete unit weight on the seismic performance of reinforced concrete columns. Three types of columns all-lightweight aggregate concrete, sand-lightweight aggregate concrete, and normal-weight concrete (NWC) were prepared with different amounts of transverse reinforcement and magnitudes of the applied axial load level. Nine columns were tested to failure under constant axial load and cyclic lateral loads. The axial force–moment interactions of column specimens were compared with the predictions obtained by ACI 318–19 procedure using the equivalent stress block and section lamina approach considering the actual stress–strain relationships of various concrete types. The curvature ductility ratios determined from the columns were compared with the ductility-based design procedure specified in EC 8. Test results showed that the moment capacity of lightweight aggregate concrete (LWAC) columns is lower than that of NWC columns, yielding that the safety of ACI 318–19 procedure slightly decreases for columns with a lower concrete unit weight and under lower applied axial load level. The ductility of columns also decreased with a decrease in concrete unit weight, revealing lower values of displacement ductility ratio and equivalent damping coefficient for LWAC columns than NWC columns. Thus, LWAC columns require more transverse reinforcement to achieve a similar seismic ductility to NWC columns under the same design conditions.

Operational Modal Analysis and Non-Linear Dynamic Simulations of a Prototype Low-Rise Masonry Building

This paper focuses on the dynamic behaviour of a low-rise masonry building representing the Italian residential heritage through experimental and numerical analyses. The authors discuss an application of combined Operational Modal Analysis and Finite Element Model updating for indirect estimation of the structural parameters. Two ambient vibration tests were carried out to estimate the structure’s dynamic behaviour in operational conditions. The first experimental setup consisted of accelerometers gathered in a row along the first floor to characterize the local dynamic of the floor. Conversely, the second setup had the accelerometers placed at the building’s corners to characterize the global dynamics. The outcomes of the first setup were used to estimate the mechanical parameters of the floor, while the ones form the second were used to characterize the mechanical parameters of the masonry piers. Therefore, two finite element models were implemented: (i) a single beam with an equivalent section of the floor to grasp the local behaviour of the investigated horizontal structure; (ii) an equivalent frame model of the entire building to characterise the global dynamic behaviour. The model updating process was developed in two phases to seize local and global dynamic responses. The updated numerical model formed the basis for a sensitivity analysis using the modelling parameters. The authors chose to delve into the influence of the floor on the dynamic behaviour of low-rise masonry buildings. With this aim, non-linear dynamic analyses were carried out under different mechanical characteristics of floors, expressing the scatter for ordinary masonry buildings. The displacements’ trends along the height of the building evidenced the notable role of the floor’s stiffness in the non-linear dynamic behaviour of the building. Lastly, the authors derived the fragility curves predicting the seismic performance in failure probability under a highly severe damage state.

Strength reserve assessment on pitting-corroded jacket offshore platforms based on the modified generalized constitutive model

The resulting localized stress concentration of the pitting corrosion causes a significant degradation in the mechanical performance and ultimate load-bearing capacity of steel jacket offshore platforms. Conventionally, the pitting-induced damage is usually treated as an equivalent section loss of a uniform corrosion case in which the local feature of corrosion pits cannot be properly reflected. Moreover, the observed variations of the macroscopic mechanical parameters with respect to the volume loss rate (VLR) are used to put forward a modified generalized constitutive model (MGCM) for the pitting-corroded steel, which can be applied for both the pitting corroded steel and intact steel, based on the uniaxial tension test conducted on the pitting-corroded specimens with different degrees of pitting damage. The MGCM, which exhibit analytical accuracy, is then combined with the fiber model in assessing the strength reserve, in terms of reserve strength ratio (RSR), of steel jacket offshore platforms with different degrees of pitting corrosion damage. Moreover, a comparison is also conducted on platforms with equivalent uniform corrosion degrees. The assessment results show that the structural performance of pitting-corroded steel jacket offshore platforms can be rationally simulated as the effect of the pitting corrosion, which is addressed in the MGCM. The overestimate, which resulted from not considering the local characteristics of pitting corrosion in structures, can be avoided. Furthermore, the effect of the pitting corrosion on the RSR of jacket offshore platforms can be easily quantified using the VLR-based variable in the MGCM, the loading bearing capacity, and other mechanical performance indexes.

Study on Soil Displacement Fields around the Expanded Body of Drill-Expanded Concrete Piles Based on DIC Technique

The soil displacement field around a drill-expanded concrete pile is noticeably different from that of an equivalent section pile placed under axial load due to the mutual embedment between the expanded body and the soil. It is important to study the soil displacement field around drill-expanded concrete piles in order to understand the mechanisms of interaction between the pile and the soil. First, the model test of the half-face pile installed in undisturbed soil and the model test of the half-face pile installed in sand were used to study the soil displacement field around the pile. Then, the entire process of the soil displacement field’s formation and development under the load was observed by using digital image correlation (DIC) techniques. Finally, numerical simulation was used to verify the results of the model tests. The results show that the displacement characteristics of the soil around the pile in the undisturbed soil and sand are basically the same. There is a clear soil compression zone under the expanded body, and the magnitude and density of the displaced soil in the compression zone are much higher than in other areas. Both the vertical displacement and the horizontal displacement gradually decrease as the distance from the expanded body and the burial depth increase. The horizontal displacement of the soil under the expanded body follows a trend of first moving toward the pile body and then moving away from it. The results of the numerical simulation are basically consistent with the results of the model test, indicating that the results of the model test are relatively reliable.

Microstructure and mechanical properties of plasma transferred wire arc spray coating on aluminum cylinder bores

This study examines the microstructure and mechanical properties of plasma transferred wire arc (PTWA) coating of typical alloyed steel, deposited on diecast aluminum alloy cylinder bores. The coating surface and microstructure were characterized in terms of surface roughness, features (i.e., defects, splats formation mechanisms, distribution of oxides, re-solidified particles, and interfacial metallurgical bonding) using laser scanning confocal microscope, scanning and transmission electron microscope (SEM and TEM). Residual stress through the thickness of the coating was measured using X-ray diffraction (XRD) and hole-drilling method. In post-processed samples, compressive residual stress was measured throughout the coating with a value close to 100 MPa at the interface, resulting from the thermal mismatch between coating and substrate materials. In terms of mechanical properties, coating hardness was estimated at both the micro- and nanoscale and examined the influence of microstructure inhomogeneity on the mechanical performance and failure modes. Three-point bending tests and consequent analysis using the equivalent section method yielded stress-strain properties for both the substrate and coating materials with a maximum coating strength averaging 1480 ± 108 MPa. SEM observation of fracture surfaces showed three modes of failure involving coating delamination and breakage, which is related to the deposition process and the various features within the coating.

Structural Analysis of the US ITER ECH Transmission Line System

The electron cyclotron heating (ECH) and current drive system is one of the main plasma heating systems for ITER. It uses high-power microwave beams with the power deposition location steerable across the plasma cross section. Microwave power is conveyed via transmission lines (TLs) that run from the gyrotrons in the radio frequency building through the assembly hall and tokamak building to the ECH launchers within the tokamak vacuum vessel. The ECH system includes a vast array of interconnected TL waveguides, in-line components, and support structures. Finite element (FE) modeling provides an essential means of simulating the system, applying loads and determining deflections, rotations, forces, moments, and stresses in order to evaluate various structural and microwave transmission performance metrics. A representative FE model of the overall ECH TL system is developed in ANSYS®. This top-level model defines the centerline of the waveguide system. Waveguide segments are represented by line elements (beams and pipes) with equivalent section properties, and support structures are represented by boundary conditions. A systematic approach is used to model each ECH component with lumped masses and structurally equivalent stiffness matrices or ANSYS superelements. The top-level TL FE model is used to evaluate the various loads (thermal, vacuum, seismic, etc.) and operating scenarios. The top-level model directly calculates stresses in the straight aluminum waveguide segments. The model provides the forces and moments acting on the in-line components for detailed submodel assessments. Displacement results from the top-level analysis feed into a separate microwave performance model to help determine operational efficiency. All TL performance and thermal-structural requirements are met, as specified by the applicable codes and standards, and successfully documented in numerous technical reports and demonstrated at the final design review.

A Novel Approach for Design and Simulation of Equivalent Continuum Model of Lattice Structures Used in Tunnels and Caverns

Developing a continuum model of a lattice structure means expressing a complicated structure into a simpler one, and this is done by determining equivalent stiffness of the original structure, which can further be used to transform into desired simpler geometry for multiple benefits. Objective of this paper is to find a reliable method for determination of equivalent stiffness of lattice girder, comparing all the techniques suggested by various researchers. In present work the actual lattice girder structures and their equivalents were analysed using Finite Element Method tool Strand7. The primary focus is on lattice girder, which is a primary rock support system employed in tunnels and caverns. The equivalent stiffness so obtained is used as input parameter in numerical analysis tool STRAND7 for analysis of equivalent lattice beam. The maximum deflection and bending stress at centre of equivalent lattice beam were calculated and compared. In an attempt to develop a more accurate equivalent beam model a novel approach which is modification of the Method-B has been developed by authors. This Noval approach is the most convenient approach to develop an equivalent section with an extremely uncompromised representation of stress development and deformation characteristic. In this approach, the focus was made on the physical resemblance of a proposed equivalent beam with the actual lattice girder, leading us to adopt a beam of I-cross-section. This approach yielded similar stress and deflections in the equivalent beam as that of the actual lattice girder.